Examples of a cutting-off processing tool include a cutting-off processing tool disclosed in the following Patent Literature 1.
The cutting-off processing tool described in Patent Literature 1 is a cutting insert having hand that includes a cutting edge angled at an end cutting edge angle. With this cutting-off processing tool, unevenness of a reactionary force against cutting force, which is applied to the cutting insert due to the effect of the end cutting edge angle, is corrected by inclining the cutting edge.
It is known that a cutting-off processing tool including a cutting edge angled at an end culling edge angle effectively addresses a problem of remaining of a projection on a workpiece, the problem arising when a cutting-off process is performed with a tool, the end cutting edge angle of which is 0°.
In a cutting-off process using a tool including a cutting edge angled at the end cutting edge angle of 0°, when part of the workpiece has not been cut yet, the workpiece is parted so as to be ripped away. As a result, a projection (unprocessed projecting part) tends to remain at the center of a processed surface of a portion of the workpiece to be cut off. In contrast, with a cutting-off processing tool, the cutting edge of which is angled at the end cutting, edge angle, cutting by a foremost end corner precedes cutting by a corner on a rear side. By doing this, the part that may otherwise remain as the projection can be cut before the workpiece is parted, thereby reducing remaining or the projection.